i think that he use the sr rear axle and rrr evo 2 center rear pulley compo.a cheap solution is to drill the alum adapters in evolva style like nt1's light versions.

i have a r4 with life,carbon wheels,some titanium rods,low prof throttle servo,side and rear weight and is at 1710gr.my rrr was lighter.so i am searching for reduce weight.